Himalayan flowers evolved for ‘bee vision’

"The finding was a surprise as flies are thought to be the main pollinator in many mountain regions, but it appears that in the Himalayas several bee species are also active at high altitude, and these insects have been such effective pollinators that they have led to the evolution of distinctive bee-friendly colors," says Mani Shrestha. (Credit: Barbara Agnew/Flickr)

Flower color has evolved to attract bees as pollinators in subtropical and steep mountain environments, a new study shows.

Previous studies have shown that flower color evolved to attract bees as pollinators in temperate environments, but the story for either subtropical or steep mountainous environments had been unknown, according to associate professor Adrian Dyer of Monash and RMIT Universities.

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The study took place in the understudied Nepalese steep mountainous terrain and other subtropical environments. Published in the Journal of Ecology, it has implications for understanding the effects of climate change on plant pollination.

“Mountainous environments provide an ideal natural experiment to understand the potential effects of changing climatic conditions on plant-pollinator interactions, since many pollinators show preferences for localized conditions, and major pollinators like honeybees do not tend to forage at high altitudes,” says Dyer.

Mani Shrestha from Monash University and colleague Prakash Bhattrai from the Tribhuvan University, Kathmandu, collected spectral data from more than 100 flowering plants in Nepal over a range of altitudes, from approximately 3,000 to over 13,000 feet.

Using computer models to examine flower colors as bees would see them, the team addressed how pollinator vision had shaped flower evolution. Then, with associate professor Martin Burd of the School of Biological Sciences, they did phylogenetic analyses to identify how altitude zones affected results.

“The finding was a surprise as flies are thought to be the main pollinator in many mountain regions, but it appears that in the Himalayas several bee species are also active at high altitude, and these insects have been such effective pollinators that they have led to the evolution of distinctive bee-friendly colors,” Shrestha says.

The research could shed light on how flower colors may continue to evolve in particular environments, depending upon the availability of the most effective pollinators.

While “bee colors” were prevalent at all elevations, flower colors in high altitude zones were more diverse and had more often undergone larger steps of evolutionary change than those at lower elevation, says Burd.

“Studying these patterns helps scientists understand how plant communities are assembled, and are potentially able to deal with changing conditions.”